title: Atrioventricular block during radiofrequency catheter ablation of atrial flutter: incidence, mechanism, and clinical implications.
abstract: OBJECTIVE
  To evaluate the incidence, mechanism, and clinical implications of atrioventricular (AV) block during catheter radiofrequency (RF) ablation of the cavotricuspid isthmus (CTI). Although RF ablation of atrial flutter is the most frequently performed ablation procedure, data on the incidence and significance of an AV block occurring during the procedure are scarce.
  
  
  RESULTS
  Consecutive patients (n=845, 73.5% male) undergoing CTI ablation (913 procedures) between 1998 and 2010 were studied. Data on the occurrence of complete AV block (lasting≥3 s) during the procedure were prospectively collected. Sixteen (1.9%) patients experienced AV block, 12 during delivery of RF pulses (Group 1) and 4 (Group 2) during manipulation of catheters in the cardiac chambers. The AV block was short lived (<1 min), located in the AV node, and associated with septal isthmus RF lines in 11 Group 1 patients. It was long-lasting and led to pacemaker implantation in one Group 1 patient. Atrioventricular blocks had an infranodal location in four Group 2 patients, all of whom had a pre-existing complete left bundle branch block (LBBB). One Group 2 patient had an AV block during his two ablation procedures. Permanent pacemakers were implanted in five (0.6%) patients (one from Group 1 and four from Group 2).
  
  
  CONCLUSIONS
  Atrioventricular blocks requiring pacemaker implantation following administration of RF pulses at the CTI are rare (0.12%). The occurrence rate of AV block related to the procedure and requiring pacemaker implantation is, however, not negligible (0.6%) and mostly affects patients with a pre-existing complete LBBB.
authors.affiliation: Department of Cardiology, Tel-Aviv Sourasky Medical Center, Tel-Aviv-University, Sackler School of Medicine, Tel-Aviv, Israel. bblhass@tasmc.health.gov.il
authors.forename: Bernard
authors.initials: B
authors.lastname: Belhassen
authors.forename: Aharon
authors.initials: A
authors.lastname: Glick
authors.forename: Raphael
authors.initials: R
authors.lastname: Rosso
authors.forename: Yoav
authors.initials: Y
authors.lastname: Michowitz
authors.forename: Sami
authors.initials: S
authors.lastname: Viskin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001282:Atrial Flutter / Q000503:physiopathology / Q000601:surgery*; D054537:Atrioventricular Block / Q000453:epidemiology* / Q000503:physiopathology* / Q000628:therapy; D017115:Catheter Ablation; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D011446:Prospective Studies; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult